Nonpolluting engine

ABSTRACT

An improved nonpolluting low-emission two cycle diesel crosshead engine designed for the control of air pollution. The engine has a combustion cylinder adapted to slidably accommodate a reciprocating piston. An upper end of the cylinder is provided with a conventional exhaust valve and a fuel injection nozzle. A plurality of apertures defined in a lower end of the cylinder interconnect the cylinder with an independent air chamber. The air chamber has a fluid pump providing an expansible interior volume to accommodate clean air displaced from the cylinder on the power stroke of the piston. A floating pump piston in the air chamber is urged toward a lower end of the chamber to intermittently force a clean, relatively cool charge of air into the cylinder for scavenging the smoke, particulates, fumes and other exhaust emissions and for supplying a clean air charge for compression. A piston lifter is adapted to return the pump piston to its initial position during the compression stroke of the piston; simultaneously, suction valves open to admit cooled and/or filtered air at atmospheric pressure into the air chamber and cylinder. A valve bypass conduit connects the cylinder and the independent air chamber to provide means for regulating the air pressure acting on the floating pump piston and to thus adjust the movement for particular operating conditions of the engine. In a modified embodiment, the independent air chamber is placed concentrically around the cylinder and is provided with a circular pump piston and piston lifter ring.

United States-Patent [191 Tonnessen [451 Apr. 3, 1973 [54] NONPOLLUTINGENGINE [76] Inventor: Tonnes K. Tonnessen, 645 46th Street, Brooklyn,NY. 1 1220 22 Filed: June3, 1971 21 Appl. No.: 149,439

[52] US. Cl ..123/74 R, 123/65 B, 123/66 R, 123/70 R [51] Int. Cl ..F02b33/12 [58] Field of Search ..l23/74 R, 74 A, 65 B, 66 R, 123/70 RV, 71RV Primary Examiner-Wendell E. Burns Attorney-Natter, Wigman & Natter[57] ABSTRACT An improved nonpolluting low-emission two cycle dieselcrosshead engine designed for the control of air pollution. The enginehas a combustion cylinder adapted to slidably accommodate areciprocating piston. An upper end of the cylinder is provided with aconventional exhaust valve and a fuel injection nozzle.

A plurality of apertures defined in a lower end of the cylinderinterconnect the cylinder with an independent air chamber. The airchamber has a fluid pump providing an expansible interior volume toaccommodate clean air displaced from the cylinder on the power stroke ofthe piston. A floating pump piston in the air chamber is urged toward alower end of the chamber to intermittently force a clean, relativelycool charge of air into the cylinder for scavenging the smoke,particulates, fumes and other exhaust emissions and for supplying aclean air charge for compression. A piston lifter is adapted to returnthe pump piston to its initial position during the compression stroke ofthe piston; simultaneously, suction valves open to admit cooled and/orfiltered air at atmosphericpressure into the air chamber and cylinder. Avalve bypass conduit connects the cylinder and the independent airchamber to provide means for regulating the air pressure acting on thefloating pump piston and to thus adjust the movement for particularoperating conditions of the engine. In a modified embodiment, theindependent air chamber is placed concentrically around the cylinder andis provided with a circular pump piston and piston lifter ring.

10 Claims, 10 Drawing Figures PATENTEDAPR3 I975 SHEET 1 [IF 2 INVENTORTONNES K. TONNESSEN FIG. 2

ATTORNEYS NONPOLLUTING ENGINE BACKGROUND OF THE INVENTION 1. Field ofthe Invention This invention relates to internal combustion engines andespecially to an improved diesel engine.

In particular, the instant invention relates to a nonpolluting,low-emission, two cycle diesel crosshead engine. The present inventionis further concerned with an engine air system for supplying clean,cooled air for the reduction of engine exhaust emissions.

2. Description of the Prior Art 7 Diesel engines presently in use employvarious engine air systems for introducing an air charge into thecylinder, e.g. crankcase compression, reciprocating air pumps, rotarydisplacement blowers and centrifugal or turbine blowers. Each of theabove mentioned air systems has distinct shortcomings and furthermore isnot specifically designed for air pollution control.

In the conventional two cycle diesel engine, an air charge is introducedinto the cylinder for scavenging combustion gases which are removedthrough an exhaust port. Some of this air will mix with the combustiongases and will inescapably remain in the cylinder for compression. Theamount of pure air retained in the cylinder for compression will varydirectly with the quantity of fresh air injected during the scavengingoperation. In some of the previously patented diesel engines, especiallytrunk types, the

crankcase is used as a compressor for injecting air into the cylinder.The volume of air drawn into the crankcase will be determined by thevolume of air displaced from the cylinder by the piston. This quantityof air will be slightly less than the volume of the cylinder because ofthe clearance volume, i.e. space between the piston head and cylinderhead. Consequently, the maximum volume of air available for scavengingand for retention in the cylinder for compression will be limited inamount. This supply of air is, in many instances, not fully sufficientfor optimum power and efficient fuel consumption. As a result, the fuelis not completely combusted and more products of incomplete combustionwill be contained in the exhaust gases. Additionally, the combustiongases will not be effectively removed in the scavenging operation. Itshould also be noted that when the lower cylinder or crank end of thecylinder is used as an air compressor, similar results are obtained.Another disadvantage of this engine air system is that the aircompressed in the crankcase will absorb heat from within the crankcaseand thereby lower the volumetric efficiency of the engine. Still anotherproblem results from the fact that lubricating oil around the movingparts in the crankcase and other impurities in the crankcase becomeentrained in the air charge injected into the cylinder; this impure airmerely adds to the pollutants already present in the cylinder.

The reciprocating air pumps and rotary displacement blowers of the priorart are conventionally driven from the engine crankshaft. These directdriven pumps and blowers have the distinct disadvantage that when theengine slows down, as with a heavy load, the volume of air injected intothe cylinder will be reduced. Since the engine requirements forscavenging and charging increase with engine load, this reduction of airinjected will effectively impair the scavenging and charging operationwith resultant inefficient combustion and an increase in pollutants.Furthermore, when initially starting the engine, the direct drivenblower must be continuously turned over with starting air until it hascompletely filled the air heads at sufficient pressure for scavengingduring which period of time there will be considerable exhaustemissions.

The centrifugal blowers are either motor driven or driven by exhaust gasturbines. However, neither type of centrifugal blower is very efficientfor compressing air to pressures above a few ounces, and furthermore,these centrifugal blowers are quite noisy. The improved diesel engine ofthis invention is designed to alleviate the foregoing disadvantages andto provide a relatively low emission pollution-free clean engine.

SUMMARY OF THE INVENTION This invention encompasses a two cycle dieselcrosshead engine, an essential feature of which is an improved airsupply system utilizing an independent air chamber interconnected withan engine cylinder for the intermittent injection of clean, pure,relatively cool air into the cylinder for scavenging combustion gasesand for charging the cylinder. The clean air effectively removes thepollutants and/or smoke contained in the cylinder exhaust gases, andsupplies a relatively pure charge of cool air for compression. The coolair substantially reduces the amount of work necessary for compression,and also provides for more efficient combustion because the cooler andconsequently denser air injected has more oxygen to effectively unitewith the hydrocarbon fuel, thus reducing the products of incompletecombustion and resultant exhaust emissions.

An important feature of the air chamber resides in a floating pumppiston which acts as a fluid spring or pump and provides an expansibleinterior volume for receiving air displaced from the cylinder. Apressure differential maintained in part by manifold air suppliedindependently to the air chamber on one side of the pump pistonintermittently urges the pump piston in a direction which forces cleanair into the cylinder for removal of combustion gases. A valve bypassconduit leading from the cylinder to the air chamber supplements themanifold air supply. The air pressure in the air chamber can thus beincreased to synchronize the pump piston movement for adjustment withthe engine operation conditions, e.g. by increasing the manifold airpressure during light load, the pump piston can be moved faster to forcean adequate air charge into the cylinder for scavenging and compressionby the more rapidly moving piston. An engine driven pump piston lifteris provided with air cushioning means for restoring the floating pumppiston to its initial position during cylinder compression;simultaneously, suction valves are opened to admit fresh air atatmospheric pressure, both to the air chamber and cylinder. The freshair so admitted may be filtered and/or pre-cooled by auxiliary means.

Another advantage of this air supply system is that not only willpollution be reduced, but the resultant clean" engine will run smoothlyand efficiently and will thus produce uniform power with a minimum ofcylinders.

Having thus summarized the invention, it will be seen that an objectthereof is to provide a nonpolluting, lowemission engine of the generalcharacter described herein which is not subject to the disadvantages ofthe prior art.

Specifically, it is an object of this invention to provide an improveddiesel engine, including an air system supplying pure air for scavengingcombustion gases from the cylinder.

Another object of this invention is to provide an improved diesel enginehaving an independent air chamber including a floating pump piston forreceiving air displaced from the cylinder and for intermittentlyinjecting a charge of cooled air into the cylinder for more efficientcompression and more complete combustion.

It is a further object of this invention to provide an improved dieselengine with a valved bypass conduit for regulating movement of thefloating pump piston and for adjusting same for the particular operatingconditions of the engine.

The above and other objects, features and advantages of the inventionwill be apparent from the following description of the preferredembodiments when considered in connection with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings, in whichare shown the preferred embodiments of the invention:

FIG. 1 is a longitudinal sectional view through the two cycle dieselcrosshead engine of this invention and shows the location andinterrelationship between an independent air chamber and a cylinder;

FIG. 2 is a sectional view taken substantially along a plane 22 of FIG.1 and shows an air passageway interconnecting the air chamber and thecylinder;

FIG. 3 is a longitudinal sectional view through a modified embodiment ofthis invention wherein an independent air chamber is arrangedconcentrically around a cylinder and further includes therein a circularpump piston and pump piston lifter ring;

FIG. 4 is a sectional view taken substantially along plane 4-4 in FIG. 3and shows an air passageway interconnecting the air chamber and thecylinder; and

FIGS. 5A-5F show schematically various phases in the operation of thetwo cycle diesel .engine of this invention and diagramaticallyillustrates the concurrent action of the independent air chamber insupplying scavenging and charging air.

DETAILED DESCRIPTION OF THE INVENTION Referring now in detail to thedrawings, the reference numeral denotes generally a two-cycle dieselengine of this invention. The diesel engine 10 is comprised of acylinder 12, a crankcase l4, and an engine air supply system includingan independent air chamber 16.

The crankcase 14 is supported on a base which includes a platform 18made up of transverse steel girders 20 and steel plates 22; appropriatevibration isolation means may be incorporated therein. Although theengine 10 as shown in FIG. 1 is arranged in a generally verticalorientation, it may be oriented horizontally and in other suitablearrangements. A plurality of vertical struts or longitudinal bolts 26extend from the base 18 through crankcase 14 to support the cylinder 12and air chamber 16. The vertical struts 26 are secured to the base 18and cylinder 12 by means of nuts 28 or other similar fasteners. Thelongitudinal struts 26 may further be reinforced by diagonal bracing 29.

A pair of channel members 30 are suitably affixed to I and supported bythe vertical struts 26 and form a track for slidably accommodating aguide or crosshead 32. A

the piston 52 moves crosshead 32 within the track; the

motion is translated into a rotary motion by the lower connecting rod 40and a crank 42 which in turn rotates a crankshaft 48 and a flywheel 50.

A cooling jacket 54 is provided circumferentially around the cylinder 12for maintaining a circulating flow of a heat absorbing fluid such aswater, to dissipate generated heat. Additionally, oil is circulatedinteriorly through ducts in the piston 52 for removing heat therein. Itshould also be noted that the upper end or head of cylinder 12 isprovided with exhaust valves 56 which can be operated by push rods in awell-known manner; a fuel injection nozzle 58 is also provided forsupplying atomized fuel under pressure. The lower end of the cylinder 12is provided with a plurality of air vents or ports 60 for permittingremoval of the air in the cylinder 12 as the piston 52 moves downwardlyon the power stroke. A plurality of suction valves 62 are designed toopen to admit fresh air into the cylinder 12 as the piston 52 movesupwardly on the compression stroke. The operation of the valves 62 willbe further discussed hereinafter. In order to insure air tightness inthe cylinder 12 appropriate packing or sealing ring 64 is placed at thepoint of entry of the upper connecting rod 38 into the cylinder 12.

The details of the nonpolluting. engine air supply system will now bediscussed in further detail. The air chamber 16 is positioned adjacentto and can be formed integrally with the cylinder 12. The lower end ofair chamber 16 is provided with a plurality of air ports or vents 66similar to vents 60. A peripherally extending side wall 68 surroundingthe cylinder 12 and air chamber 16 serves as a conduit or passageway forthe transferof air therebetween.

The air chamber 16 is. further provided with a pump piston 70 having anupwardly extending guide 72 adapted to be slidingly accommodated withintubular guide way 74, thus assuring proper alignment of the pump piston70 during reciprocating movement within the air chamber 16. An airmanifold 76 is used to supply air under relatively constant pressure tothe air chamber 16. A pump piston lifter 78 is slidably accommodatedwithin the air chamber 16 and designed for coaction with the pump piston70. Accordingly, the pump piston lifter 78 is provided with a push rod80, which is in turn securely attached to a cross arm 82 and is designedto move with the crosshead 32. It will thus be apparent for example,that as the crosshead 32 moves upwardly on the compression stroke, thepush rod 80 and pump piston lifter 78 will likewise move upwardly withinthe air chamber 16 and move the pump piston 70 in the same direction.

Air tightness is maintained in the air chamber 16 by use of appropriatepacking or sealing ring 83 provided around the push rod 80 at its pointof entry into the air chamber 16.1110 pump piston lil'ter 78 is providedwith a peripheral flange portion 80 having a plurality of apertures 79passing therethrough so as to permit air flow around the pump pistonlifter 78 when air is being forced into the air chamber 16, as on thepower stroke of the piston 52. As the pressure of this air increases toor becomes greater than the manifold air pressure on the opposite sideof the pump piston 70, it will cause the pump piston 70 to float or moveupwardly to thereby provide an expansible interior volume in air chamber16 for accommodating air displaced from cylinder 12 without creating anyundue opposing workload on piston 52 during the power stroke. In anattempt to reduce undue wear on moving the parts within air chamber 16,direct contact between piston 70 and lifter 78 is avoided by means of anair cushion. This is achieved by having the pump piston lifter 78provided with a raised portion 84 adapted to be received in a recess 86formed in the piston 70. The aforementioned apertures 79 allow some ofthe air between the pump piston 70 and the pump piston lifter 78 toescape as these members approach each other; however, a layer of airwill be trapped therebetween to form an air cushion.

A plurality of suction valves 88 are provided in the lower portion ofthe air chamber 16. These suction valves operate to admit fresh air asthe pump piston lifter 78 moves upwardly in the air chamber 16. The airwhich enters through the suction valves 88 as well as suction valves 62may be supplied from a separate auxiliary source (not shown) and can bepre-cooled and/or filtered air. Furthermore, the air contained withinthe air chamber 16 may be cooled directly while therein. It should alsobe apparent that the quantity of air within the air chamber 16 isdirectly dependent on the size of said chamber and accordingly thequantity may be varied in accordance with optimum operating conditionsfor the diesel engine.

In addition to the air supplied by manifold 76, a bypass conduit 90having a valve 92 interconnects the cylinder 12 and the upper portion ofthe air chamber 16 for supplementing the manifold air supplied.

The operation of the two cycle diesel engine of this invention and thenonpolluting air system will be described in further detail withreference to the schematic drawings as shown in FIGS. 5 (A-F). Theillustration A shows the piston 52 is a top dead center position duringthe compression stroke wherein an air charge within the cylinder hasbeen compressed. At this moment the pump piston 70 and pump pistonlifter 78 are at their uppermost position with manifold air pressure ofapproximately 6 p.s.i.g. (in a typical example) being maintained in theupper portion or compartment of air chamber 16. The lower portion orcompartment of the air chamber 16 is maintained at atmospheric pressureand contains clean air which enters through suction valve 88 as the pumppiston lifter 78 moves upwardly in the air chamber 16. The suction valve62 similarly allows clean air to enter the cylinder 12. In illustration8" rapid expansion of the combustion gases drives the piston 52downwardly in the cylinder 12, thereby displacing the air thereinthrough air vents 60 and into the air chamber 16 via air vents 72. Theair pressure within the lower portion of chamber 16 has been typicallyraised to 2 p.s.i.g. Illustration C" shows the piston 52 in aprogressively lower position wherein more of the air within cylinder 12has been displaced into the air chamber 16 and thc air pressure withinthe lower portion of chamber 16 has been gradually increased totypically 4-5 p.s.i.g. wherein some of the air is beginning to passthrough the pump piston lifter 78. Illustration D shows the piston 52 ata point before bottom dead center wherein the air pressure within lowerportion of air chamber 16 is equal to the manifold air pressure and thepump piston 70 is floating and responsive to upward movement to increasethe interior volume of the lower portion of the air chamber 16 to thusaccommodate more air therein and to reduce the resistance to downwardmovement of piston 52. It should be noted that exhaust valves 56 are nowopen.

In illustration E, the piston 52 has descended to the bottom dead centerposition clearing the air vents 60 and permitting entry of the air fromthe air chamber 16. This scavenging air will be forced into the cylinder12 by pump piston 70. The quantity of scavenging air will in part bedetermined by the volume of the air chamber 16 and accordingly thechamber 16 may be designed so that optimum quantities of air may beinjected into the cylinder 12. It should be noted that the flow of airthrough the cylinder 12 is in one direction, i.e. unidirectional,thereby driving a maximum amount of burnt gases out through exhaustvalves 56. It should be additionally noted that since this scavengingair is relatively fresh, pure, clean, filtered and pre-cooled, a morethorough cleaning operation is feasible and that the scavenging airitself will not add to the pollutants entrained within the exhaustgases. Since some of this air remains in the cylinder 12 to provide anair charge, the air will preferably be relatively cool, i.e. dense,containing an optimum amount of oxygen for combining with thehydrocarbons in the fuel. As a direct result, this engine will not onlybe nonpolluting, but will run smoother with more uniform power and thisincreased efficiency will minimize the number of cylinders needed forany requisite power requirements.

Illustration F shows the piston 52 moving upwardly to compress this newair charge. The suction valves 62 in the cylinder 12 and suction valves88 in air chamber 16 are open at this point to admit fresh air atatmospheric pressure. The pump piston lifter 78 moves the pump pistonupwardly. However, as previously mentioned, an air cushion is maintainedtherebetween to reduce undue wear and to cushion contact between thesetwo members. It should be pointed out that the relative air pressuresreferred to hereinabove are mentioned by way of example only and thatother pressures to suit particular operating conditions can bemaintained. In that respect, another feature of this invention includesmeans for regulating the pressure within the air chamber 16,particularly during varying engine operating conditions. This isachieved by means of a bypass conduit 90 which interconnects the upperportion of the air chamber 16 with the lower portion of the cylinder 12whereby the valve 92 may be regulated to admit air from the cylinder 14in varying quantities to as to supplement the manifold air pressure inthe air chamber 16.

In an alternate embodiment, wherein like numerals are used to designatelike parts with the suffix letter a being used in this embodiment; theFIGS. 3 and 4 show a two cycle diesel engine a provided with an airchamber 16a positioned circumferentially around a cylinder 12a. Theengine 10a is mounted on a platform 18a and has a crankcase 140 housinga crankshaft 48a, a crank 42a and a forked end connecting rod 40amounted to the crank 42a. A piston 52a provided for slidableaccommodation within cylinder 12a is attached to an upper connecting rod380 which has its end secured to the forked end of connecting rod 40a bymeans of a journalled connecting rod pin 34a. The air chamber 16a isprovided with a circular pump piston 70a. However, no guide means isrequired because the ring configuration of pump piston 70a will assureproper alignment for reciprocating movement within the air chamber 16a.An annular recess 86a in the face of circular pump piston 70a is inconfronting relationship with a conforming pump piston lifter ring 78a.The annular recess 86a is adapted to receive the pump piston lifter ring78a and to create an air cushion therebetween similar to the air cushionformed in the aforementioned embodiment. The piston lifter ring 78a ismoved within the air chamber 16a by means of push rods 80a which aresecurely affixed to the connecting rod pin 34a. It should be noted thata space 82a exists between the wall of the air chamber 16a and the ring78a so that air may pass around the ring 78a to act on the piston 70a.The cylinder 12a has a plurality of air vents 60a which are connected bya passageway 94 to corresponding air vents 66a provided in air chamber16a.

The operation of this modified embodiment will be similar in detail tothe previously described embodiment. The FlG. 3 shows the engine 10aduring the power stroke of piston 52a wherein exhaust valves 56a areclosed and the air in cylinder 12a is being displaced through air vent60a into air chamber 16a. The air pressure is being maintained in theupper portion of air chamber 16a by means of air introduced throughmanifold 76a, which is resiliently urging the circular pump piston 70ain a downward direction. As the pressure below the circular pump piston70a builds up, this circular pump piston 70a will float or move upwardto form an expansible interior volume in the lower portion of airchamber 16a and will act as a reservoir for receiving air displaced fromcylinder 12a. The air so received in chamber 16a will be forced underpressure back into cylinder 12a when piston 52a has reached a point nearthe bottom of cylinder 12a thereby exposing air vents 60a for entry ofthe scavenging air. As the piston 52a and pump piston lifter ring 78amove upwardly, suction valves 88a and 62a permit fresh, pure air atatmospheric pressure to respectively enter air chamber 16a and cylinder14a. A bypass conduit may be introduced to regulate the air pressure inair chamber 16a in the same manner as was previously described withrespect to the other embodiment.

The preferred embodiment of this invention described a particularapplication with respect to two cycle diesel crosshead engines, itshould be further apparent that this engine air supply system may beadaptable in other internal combustion engines.

Since various possible embodiments might be made of the presentinvention, and as numerous changes might be made in the embodiment setforth, it is to be understood that all matter herein described or shownin the accompanying drawings is to be interpreted as illustrative andnot in a limiting sense.

Having thus described the invention, there is claimed as new and desiredto be secured by Letters Patent:

1. A nonpolluting internal combustion engine capable of deliveringsmooth, uniform power with a minimum of exhaust pollutants comprising acombustion cylinder, a piston slidably accommodated for reciprocalmovement within said cylinder, connecting means mechanically linkingsaid piston to a crankshaft, a crankcase for housing said connectingmeans and crankshaft, air supply means having an independent airchamber, air passage means between said air chamber and cylinder, fluidpump means including pump piston means slidably accommodated within theair chamber for volumetric expansion to receive air displaced from thecylinder during movement of thepiston in a first direction, said pumppiston means being correspondingly adapted for movement from an initialposition to a charging position for injection of a quantity of clean airinto the cylinder to scavenge combustion gases and to supply an airchange and a pump piston lifter for returning the pump piston to theinitial position upon movement of the piston in a second directionwhereby the air charge is compressed in the cylinder.

2. A nonpolluting engine as claimed in claim 1 wherein the lower end ofthe cylinder is provided with a plurality of ports in communication withthe air passage means, said ports being closed, after evacuation of theclean air in the lower portion of the cylinder, by passage of the pistonin the first direction and alternately opened to admit the clean aircharge from the air chamber prior to movement of the piston in thesecond direction.

3. A nonpolluting engine as claimed in claim 2 wherein the pump pistonlifter is mechanically interconnected for simultaneous movement with thepiston.

4. A nonpoluting engine as claimed in claim 1 wherein the pump pistonsubstantially divides the air chamber into two compartments, one of thesaid compartments being in communication with the cylinder, the other ofsaid compartments being maintained at a predetermined air pressure forcontrolling movement of the pump piston.

5. A nonpolluting engine as claimed in claim 4 further including abypass conduit from the cylinder for supplementing the air supplied tothe air chamber, and valve means in the bypass conduit for permittingregulation of the air flow to the air chamber in accordance with theoperating conditions of the engine.

6. A nonpolluting engine as claimed in claim 2 wherein the air chamberis arranged concentrically around the cylinder and the fluid pump meansincludes a pump piston slidably accommodated within the air chamber formovement from an initial position to a charging position whereby air isforced through the air passage and into the cylinder and further thepump piston lifter ring is in confronting relationship with the pumppiston for returning the pump piston to its initial position.

7. A nonpolluting engine as claimed in claim 2 including guide means foraligning the pump piston within the air chamber, the pump piston beingfurther tomatically providing a supply of fresh air at atmosphericpressure during compression of the air charge.

10. A nonpolluting engine as claimed in claim 9 further including asuction valve in the air chamber for automatically providing a supply offresh air at atmospheric pressure to the air chamber during movement ofthe pump piston to the initial position.

1. A nonpolluting internal combustion engine capable of deliveringsmooth, uniform power with a minimum of exhaust pollutants comprising acombustion cylinder, a piston slidably accommodated for reciprocalmovement within said cylinder, connecting means mechanically linkingsaid piston to a crankshaft, a crankcase for housing said connectingmeans and crankshaft, air supply means having an independent airchamber, air passage means between said air chamber and cylinder, fluidpump means including pump piston means slidably accommodated within theair chamber for volumetric expansion to receive air displaced from thecylinder during movement of the piston in a first direction, said pumppiston means being correspondingly adapted for movement from an initialposition to a charging position for injection of a quantity of clean airinto the cylinder to scavenge combustion gases and to supply an airchange and a pump piston lifter for returning the pump piston to theinitial position upon movement of the piston in a second directionwhereby the air charge is compressed in the cylinder.
 2. A nonpollutingengine as claimed in claim 1 wherein the lower end of the cylinder isprovided with a plurality of ports in communication with the air passagemeans, said ports being closed, after evacuation of the clean air in thelower portion of the cylinder, by passage of the piston in the firstdirection and alternately opened to admit the clean air charge from theair chamber prior to movement of the piston in the second direction. 3.A nonpolluting engine as claimed in claim 2 wherein the pump pistonlifter is mechanically interconnected for simultaneous movement with thepiston.
 4. A nonpoluting engine as claimed in claim 1 wherein the pumppiston substantially divides the air chamber into two compartMents, oneof the said compartments being in communication with the cylinder, theother of said compartments being maintained at a predetermined airpressure for controlling movement of the pump piston.
 5. A nonpollutingengine as claimed in claim 4 further including a bypass conduit from thecylinder for supplementing the air supplied to the air chamber, andvalve means in the bypass conduit for permitting regulation of the airflow to the air chamber in accordance with the operating conditions ofthe engine.
 6. A nonpolluting engine as claimed in claim 2 wherein theair chamber is arranged concentrically around the cylinder and the fluidpump means includes a pump piston slidably accommodated within the airchamber for movement from an initial position to a charging positionwhereby air is forced through the air passage and into the cylinder andfurther the pump piston lifter ring is in confronting relationship withthe pump piston for returning the pump piston to its initial position.7. A nonpolluting engine as claimed in claim 2 including guide means foraligning the pump piston within the air chamber, the pump piston beingfurther provided with receiving means for accommodating the pump pistonlifter in close fitting relationship, whereby a layer of air is retainedtherebetween, thus forming an air cushion.
 8. A nonpolluting engine asclaimed in claim 7 wherein the pump piston lifter defines aperturestherethrough for permitting the passage of air displaced from thecylinder.
 9. A nonpolluting engine as claimed in claim 4 furtherincluding a suction valve in the cylinder for automatically providing asupply of fresh air at atmospheric pressure during compression of theair charge.
 10. A nonpolluting engine as claimed in claim 9 furtherincluding a suction valve in the air chamber for automatically providinga supply of fresh air at atmospheric pressure to the air chamber duringmovement of the pump piston to the initial position.